Provided is a plasma processing apparatus capable of obtaining desired etch profiles and preventing the degradation of yield rates due to the adhesion of particles, and equipped with a processing chamber in which a sample is plasma-treated; a radio-frequency power source for supplying radio-frequency power used to generate plasma; a sample stage which is provided with electrodes for electrostatically adsorbing the sample and on which the sample is mounted; and a DC power supply for applying DC voltages to the electrodes, the apparatus being further equipped with a control apparatus for controlling the DC power supply so as to apply such DC voltages as to decrease the absolute value of the potential of the sample in the absence of the plasma.